EEG Source estimation without brain image

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1

Hi.

I try to do source estimation of EEG without brain image.

I installed Freesurfer and make a fiduciary brain image by
create_default_subject. But these created file only suitable for MEG
analysis.

So I try to make bem mesh by watershed algorithm command.

But after run this function, the error occurred saying Freesurfer isn?t
exist.

I set up Freesurfer as directed in Freesurfer wiki. Also I past license
file in Freesurfer home directory.

How to fix it?

Best regards,
Hiroyasu Watanabe
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2

Hi Hiroyasu,

Please post the precise commands used, and the exact error message(s). It does sound like Freesurfer is not in your (Unix) PATH, can you run `recon-all -help` on the command line (terminal)?

That said, the ?default' subject is indeed only prepared for a single BEM-shell, MEG-only forward model. Although it would be possible to create a 3-layer BEM for EEG use, depending on your data (3D electrode coordinates exist?), exact application and source estimation method of choice, it may make little sense.

Have you considered creating a spherical (4-layer) head model instead?

https://www.martinos.org/mne/stable/generated/mne.make_sphere_model.html

This can be passed to

https://www.martinos.org/mne/stable/generated/mne.make_forward_solution.html

along with the source space and MRI-head transformation obtained using create_default_subject.

/Chris